Methods and systems for overriding graphics commands

ABSTRACT

Disclosed are “graphics overrides.” An override accepts a stream of graphics commands as produced by an application and then modifies the stream before it is rendered by the GPU. Different overrides perform different modifications. One override can modify a stream of graphics commands in response to another stream. Overrides can enforce conformity with a visual paradigm and, by being modified, can support a change to that paradigm without requiring the applications to change. Overrides can monitor the entire computing environment and improve the response to that environment of a particular application: For example, an override monitors frames as they are produced by an application. If the application cannot keep up with a fixed frame rate, then the override produces “synthetic” frames to take the place of missing frames. Overrides are not restricted to fixing existing problems. Rather, applications can be developed that depend upon the presence of overrides.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. patent applications (MotorolaDocket Numbers CS40783 and CS40930), filed on an even date herewith andincorporated by reference herein in their entireties.

TECHNICAL FIELD

The present disclosure is related generally to computer graphicsprocessing and, more particularly, to displaying information on acomputer screen.

BACKGROUND

In a modern computing device, applications, utilities, and the operatingsystem all run on, and share the processing power of, a centralprocessing unit (“CPU”).

(Note 1: Computing devices now commonly parse out their work amongmultiple processors. For clarity's sake, the present discussion uses theterm “CPU” to cover all single- and multiple-processor computingarchitectures.)

(Note 2: The phrase “applications, utilities, and the operating system”is shorthand for the set of all entities that may present information toa computer screen. Distinctions among these entities are, for the mostpart, of little import to the present discussion. Therefore, forclarity's sake, all of these entities are all usually called“applications” from here on unless a particular distinction is beingdrawn.)

When an “application” needs to present visual information to a user of acomputing device, rather than directly issuing commands to the hardwarethat controls a display screen of that device, the application writes aseries of graphics commands. These commands are sent to a graphicsprocessing unit (“GPU”) which interprets the commands and then draws onthe display screen.

Because the applications, utilities, and the operating system running onthe device may all send graphics commands to the GPU, conflicts amongthe commands may arise. As a simple example, an application may commandthat a window be opened in a portion of the screen in which theoperating system wishes to draw a background image (or “wallpaper”). TheGPU knows the presentation hierarchy established among the applications(i.e., which one's display information should be “on top” and shouldthus overwrite that of the others) and resolves any conflictsaccordingly. In the present example, the application is on top, so itswindow occludes a portion of the background wallpaper displayed by theoperating system. Instead of occlusion, the GPU can be commanded tomerge disparate images to make, for example, an “upper” imagesemi-transparent so that a “lower” image can be seen through it.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

While the appended claims set forth the features of the presenttechniques with particularity, these techniques, together with theirobjects and advantages, may be best understood from the followingdetailed description taken in conjunction with the accompanying drawingsof which:

FIG. 1 is a generalized schematic of a computing device in which thepresent techniques may be practiced;

FIG. 2 is a dataflow diagram showing overrides being applied to streamsof graphics commands;

FIG. 3 is a flowchart of a representative method for applying a graphicsoverride;

FIG. 4 is a flowchart of an alternative method for applying a graphicsoverride;

FIGS. 5 a and 5 b together form a flowchart of a representative methodfor creating synthetic frames;

FIG. 6 is a rendering timeline for a series of application-produced andsynthetic frames;

FIG. 7 is a flowchart of a representative method for a server to gatheruser-response data;

FIG. 8 is a flowchart of a representative method for an end-user deviceto gather user-response data; and

FIG. 9 is a schematic diagram of a selection process driven byuser-response data.

DETAILED DESCRIPTION

Turning to the drawings, wherein like reference numerals refer to likeelements, techniques of the present disclosure are illustrated as beingimplemented in a suitable environment. The following description isbased on embodiments of the claims and should not be taken as limitingthe claims with regard to alternative embodiments that are notexplicitly described herein.

Powerful as it is, the existing model in which applications sendgraphics commands to be implemented by a GPU presents significantlimitations. A first limitation is based on what may be called the“too-many-authors” problem: In current open computing architectures,applications are developed by a disparate set of authors, and theapplications are hosted by a computing device running an operatingsystem and utilities written by yet other authors. It would besurprising if all of these authors together accidentally presented aunified visual scene. Existing GPUs are not intelligent enough toradically transform the visual information they are commanded topresent, therefore if a designer of a computing device wishes to haveall of the applications running on the device conform to a given visualparadigm, then one option would be to constrain the applications to useonly a restricted set of graphics commands (a set that, for example,does not allow changing certain fixed parameters). Of course, thisreduces the flexibility of the developed applications, and that could beannoying to authors and to users alike. Also, because there are so manydifferent applications controlled by no single authority, it may becomeessentially impossible to update all of the applications when the visualparadigm is changed.

A second, and more reasonable, response to the too-many-authors problemis to allow the authors the use of the full set of graphics commands butto publish guidelines for implementing the visual paradigm. Often,however, application authors fail to follow the guidelines, eitherthrough a misunderstanding or in order to achieve an effect not allowedfor by the guidelines. And, as with the first option, there may be nofeasible update path when the paradigm shifts.

A second limitation posed by the application-to-GPU model may be calledthe “too many externalities” problem: It is very difficult to draft anapplication that can account for everything in the computing environmentoutside of the application itself that may be running concurrently onthe computing device, especially as that “everything” may includeapplications and other software written by the disparate set of authorsmentioned above. When computing resources are in high demand, a givenapplication may begin to fail or to operate in an unanticipated fashion.As the computing environment changes with the addition of more anddifferent applications, it becomes unrealistic to assume that all of theapplications are written in such a manner that they can handle thestrain. Because of the too-many-authors problem, it is also unrealisticto assume that these applications can all be upgraded as needed wheneverthe computing environment changes.

To address these and other limitations of the application-to-GPU model,the present disclosure introduces the concept of a “graphics override.”The override accepts a stream of graphics commands as produced by anapplication and then modifies the stream before it is rendered by theGPU.

Generally speaking, the earliest overrides are implemented as code (oras parameters for a more generic code) to run on the CPU. In the future,it is expected that some overrides will be hosted directly by the GPU.

Different overrides perform different modifications. As a simpleexample, one override can review all of the incoming graphics commandsfrom all applications and other software, find the commands that callfor text to be displayed, and modify those commands so that they conformto a standard (e.g., they all use the same font and contrast).

Overrides can be very general or very specific in their focus. Oneoverride can modify a stream of graphics commands in response to anotherstream. Overrides can enforce conformity with a visual paradigm and, bybeing modified, can support a change to that paradigm without requiringthe applications to change. Overrides can monitor the entire computingenvironment and improve the response to that environment of a particularapplication. In an example explained in detail below, an application issupposed to produce frames at a fixed rate. An override monitors theframes as they are produced by the application. If the applicationcannot keep up with the fixed rate, then the override produces“synthetic” frames to take the place of missing frames. Thus, theoverrides prevents the application from producing jerky output when theload on the CPU is heavy.

Overrides are not restricted to fixing existing problems. Rather,applications can be developed that depend upon the presence ofoverrides. In another example detailed below, overrides support “A/Btesting” of a new software product. A product is sent to two sets ofusers. Each set is also given a particular override. The first set ofusers experiences the product as modified by a first override, and thesecond set experiences the same product but with a second override inplace. User-response data are gathered to see which override ispreferred. The “winning” override is then incorporated into the releaseversion of the product. Future overrides can be sent to further modifythe user experience, either to support further testing or to implementan altered experience.

To understand these concepts more fully, first consider therepresentative computing device 100 of FIG. 1. The device 100 is meantto represent any computing device that presents visual information. Itcould be, for example, a personal communications device with a displayscreen, a mobile telephone, a personal digital assistant, or a personalor tablet computer. In some embodiments, the device 100 presents visualinformation to be displayed on a screen separate from the device 100itself, such as a set-top box, gaming console, or server. The device 100could even be a plurality of servers working together in a coordinatedfashion.

The CPU 102 of the device 100 includes one or more processors (i.e., anyof microprocessors, controllers, and the like) or a processor and memorysystem which processes computer-executable instructions to control theoperation of the device 100. The device 100 can be implemented with acombination of software, hardware, firmware, and fixed-logic circuitryimplemented in connection with processing and control circuits,generally identified at 104. Although not shown, the device 100 caninclude a system bus or data transfer system that couples the variouscomponents within the device 100. A system bus can include anycombination of different bus structures, such as a memory bus or memorycontroller, a peripheral bus, a universal serial bus, and a processor orlocal bus that utilizes any of a variety of bus architectures.

The computing device 100 also includes one or more memory devices 106that enable data storage, examples of which include random-accessmemory, non-volatile memory (e.g., read-only memory, flash memory,EPROM, and EEPROM), and a disk storage device. A disk storage device maybe implemented as any type of magnetic or optical storage device, suchas a hard disk drive, a recordable or rewriteable disc, any type of adigital versatile disc, and the like. The device 100 may also include amass-storage media device.

The memory system 106 provides data storage mechanisms to store devicedata 114, other types of information and data, and various deviceapplications 112. An operating system 108 can be maintained as softwareinstructions within the memory 106 and executed by the CPU 102. Thedevice applications 112 may also include a device manager, such as anyform of a control application or software application. The utilities 110may include a signal-processing and control module, code that is nativeto a particular component of the device 100, a hardware-abstractionlayer for a particular component, and so on.

The computing device 100 also includes an audio-processing system 116that processes audio data and controls an audio system 118 (which mayinclude, for example, speakers). A GPU 120 processes graphics commandsand visual data and controls a display system 122 that can include, forexample, a display screen. The audio system 118 and the display system122 may include any devices that process, display, or otherwise renderaudio, video, display, or image data. Display data and audio signals canbe communicated to an audio component or to a display component via aradio-frequency link, S-video link, High-Definition MultimediaInterface, composite-video link, component-video link, Digital VideoInterface, analog audio connection, or other similar communication link,represented by the media-data ports 124. In some implementations (e.g.,a set-top box which drives a television monitor), the audio system 118and the display system 122 are components external to the device 100.Alternatively (e.g., in a cellular telephone), these systems 118, 122are integrated components of the device 100.

The computing device 100 can include a communications interface whichincludes communication transceivers 126 that enable wired or wirelesscommunication. Example transceivers 126 include Wireless Personal AreaNetwork radios compliant with various IEEE 802.15 standards, WirelessLocal Area Network radios compliant with any of the various IEEE 802.11standards, Wireless Wide Area Network cellular radios compliant with3GPP standards, Wireless Metropolitan Area Network radios compliant withvarious IEEE 802.16 standards, and wired Local Area Network Ethernettransceivers.

The computing device 100 may also include one or more data-input ports128 via which any type of data, media content, or inputs can bereceived, such as user-selectable inputs (e.g., from a keyboard, from atouch-sensitive input screen, or from another user-input device),messages, music, television content, recorded video content, and anyother type of audio, video, or image data received from any content ordata source. The data-input ports 128 may include USB ports,coaxial-cable ports, and other serial or parallel connectors (includinginternal connectors) for flash memory, storage disks, and the like.These data-input ports 128 may be used to couple the device 100 tocomponents, peripherals, or accessories such as microphones and cameras.

Before considering detailed techniques for using overrides (see thediscussion below accompanying FIGS. 3 through 9), turn to FIG. 2 whichgives examples of where overrides can be implemented in the processingarchitecture. Running on the CPU 102 of the computing device 100 are anoperating system 108, a utility program 110, and an application 112.

In FIG. 2, the operating system 108 is operating according to priorconventions, that is, without an override. The operating system 108produces a stream of graphics commands 200 a that are sent to the GPU120. The GPU 120 implements these commands 200 a as appropriate andthereby controls the display system 122. (Note: As discussed above,commands from various sources 108, 110, 112 running on the CPU 102 mayconflict, so the GPU 120 implements all commands “as appropriate” byconsidering the display context and the hierarchy of the sources 108,110, 112 of the graphics commands. Thus, the GPU 120 may perform somegraphics commands exactly as specified, may ignore others, and mayperform still others in a manner different from what the commandsexplicitly call for.)

Next consider the utility 110. It produces its own stream of graphicscommands 200 b. However, before those commands 200 b get to the GPU 120,they are intercepted by the CPU-hosted override 202. That override 202examines and amends its incoming stream 200 b. It then sends an amendedstream 200 c to the GPU 120 which processes the amended stream 200 cjust as it would process any other stream of graphics commands (payingattention, of course, to the source and context of that stream).

Finally, the application 112 produces its stream of graphics commands200 d which are dutifully sent to the GPU 120. Before implementing thesecommands 200 d, however, the GPU-hosted override 204 intercepts them andmodifies them to produce the amended stream 200 e. This amended stream200 e is then processed within the GPU 120. (Note that most current GPUscannot host overrides such as 204. However, as GPUs become more powerfuland flexible, it is anticipated that this will become a useful adjunctto CPU-hosted overrides like 202.)

Note that the assignment of the three techniques in FIG. 2, i.e., nooverride to the operating system 108, a CPU-hosted override 202 to theutility 110, and a GPU-hosted override 204 to the application 112 iscompletely arbitrary. Any type of software process 108, 110, 112 may useany of these techniques and may even use more than one technique at thesame time. Thus, the amended stream 200 c produced by the CPU-hostedoverride 202 may itself be intercepted by another CPU-hosted override oreven by a GPU-hosted override. Also, some of the graphics commands 200 dproduced by the application 112 may go to the override 204 while othercommands go to another override. These are straightforward matters ofimplementation and management of the presently disclosed techniques.

With this general background in mind, turn to FIG. 3 which presents arepresentative method for using a CPU-hosted override such as theoverride 202 of FIG. 2.

The method begins at step 300 where a stream of graphics commands 200 bis produced as output by an source application 108, 110, 112. In someembodiments, the source 108, 110, 112 is not aware of the fact that itsoutput is going to an override. In contrast with this, the discussionaccompanying FIGS. 7 through 9 presents a circumstance in which thesource application is written to depend upon the presence of anoverride.

In optional step 302, a second stream of graphics commands is received.This step (along with optional step 306 discussed below) emphasizes thatthe relation between sources 108, 110, 112 and overrides need not beone-to-one: A single override may accept graphics commands from multiplesources 108, 110, 112.

In step 304, the override 202 is applied to its input stream of graphicscommands 200 b and produces an amended output stream of graphicscommands 200 c.

The override 202 is a code instance separate from the source 108, 110,112 of the stream of graphics commands 200 b. Although separate, in someembodiments, the override 202 can be given full access to informationabout the internal status of the source 108, 110, 112 and about thecontext in which that source 108, 110, 112 is running (see the exampleof FIGS. 5 and 6, discussed below), including, for example, therelationship of the current source to other applications and possiblythe environment beyond the computing device 100 (e.g., an override mayaccess the Web to gather important information). On the other hand,other overrides may be limited in their knowledge (for security's sake)and may not even be aware of the source 108, 110, 112 of the inputstream 200 b but may simply process the input stream 200 b withoutregard to the identity or nature of the source 108, 110, 112 of thatstream 200 b.

In general, an override 202 can be developed to perform any type ofamendment to the input stream 200 b, including adding, deleting,modifying, and re-arranging graphics commands. The amendment may simplychange a single parameter in a single graphics command as, for example,when the input “stream” 200 b has a single command to draw a blue box,and the amended output stream 200 c has a single command to draw a redbox. Or the override 202 can change all text commands so that the output200 c (and potentially the output from all sources 108, 110, 112) has aconsistent font or other appearance parameter.

In some cases, the output stream 200 c stream may be null, that is, theoverride 202 cancels, at least for a time, the visual output of thesource 108, 110, 112.

The processing performed by a given override 202 can be very simple, asshown by the examples given above, or very complex. For example, anoverride 202 may receive as input a static image 200 b and change theimage's perspective (e.g., tilt or scale it) or even add motion to theimage 200 b to produce a video output 200 c. A sophisticated override202 may generate, from the input graphics command stream 200 b, a scenegraph (as known in the art). The scene graph may then be modified, andthe output stream of graphics commands 200 c may then be createddirectly from the modified scene graph and, thus, only indirectly fromthe input stream of graphics commands 200 b. Although creating andinterpreting a scene graph requires a good deal of processing power, itis a good option for some overrides 202 because the override 202 canthen apply existing graphics tools (e.g., an element identifier, shader,properties module, or physics engine) to the created scene graph toproduce sophisticated effects. The override 202 may be implemented as aset of instructions or rules that take account of the current contextand of past developments (i.e., the override 202 can have a memory). Therules of the override 202 may even specify when to invoke itself oranother override.

In optional step 306, the override 202 is applied, at least in part, tothe second input stream (see step 302) to produce a second outputstream. Note that this technique can be applied to allow the override202 to coordinate among multiple instances of the same, or different,sources 108, 110, 112. For example, multiple players of a game may eachrun a separate instance of a game application 112. The override 202receives the output graphics streams of all of the game-applicationinstances, harmonizes them, and then either produces a separate outputgraphics stream 200 c for each user, or a single output stream 200 c forall the users (i.e., the first and second output streams 200 c of steps304 and 306 may be the same stream 200 c, or the output streams 200 cmay each be based on the totality of the input streams 200 b). Inanother example, an override 202 can accept the outputs of multipleapplications 112 and modify those outputs so that they fit into aunified user interface, perhaps by tiling the separate inputs or byblending them together.

The output streams 200 c produced by the override 202 are sent in step308 to the GPU 120. The streams 200 c may be identified to the GPU 120as produced by their ultimate sources 108, 110, 112 or as produced bythe override 202 itself (As discussed above, the GPU 120 uses thissource information for resolving conflicts among graphics commands.)

The GPU 120, which in the method of FIG. 3 may be an existing GPU,renders, in step 310, the graphics streams it receives, includingnon-amended streams such as 200 a (e.g., a status update message fromthe operating system 108; see FIG. 2) and amended streams such as 200 c.The rendering may be done directly to a display screen on, or hosted by,the computing device 100. In some situations, the rendered output of theGPU 120 may be sent to a communications interface 126 (as when a serverperforms graphics processing too burdensome for an end-user device) orstored in a memory system 106.

FIG. 4 presents a method for implementing a GPU-hosted override, such asthe override 204 of FIG. 2. The considerations and details discussedabove in relation to the CPU-hosted override 202 apply as well to thiscase and need not be repeated. In step 400, the GPU 120 receives aninput stream of graphics commands 200 d (see FIG. 2). In step 402, theGPU 120 receives the override 204 from the CPU 102. (There is nosignificance to the ordering of steps 400 and 402: The override 204 mayhave been received in step 402 long before the stream of graphicscommands 200 d arrives and may even reside permanently on the GPU 120.)The override 204 amends the incoming stream of graphics commands 200 din step 404 to produce an amended output stream (not shown in FIG. 2).The GPU 120 renders that output stream as appropriate.

It is anticipated that, in particular situations, hosting an override onthe GPU 120 will have certain advantages over hosting a similar overrideon the CPU 102. Different GPUs support different features and havedifferent strengths and weaknesses, so an override tailored to aparticular GPU architecture may be more efficient than a CPU-hostedoverride. In a computing architecture where multiple CPUs provide inputto a single GPU, the GPU may be the best place to coordinate a unifieddisplay paradigm.

FIGS. 5 and 6 present the case of a particular override that accountsfor factors outside of the control of the source application 112 itself.Consider an application 112 that produces frames at a fixed rate. Insome examples, the application 112 need only retrieve already existingframes from, say, the memory system 106 and present them to the GPU 120.In other examples, such as an interactive computer game or an enhancedreality display, the application 112 creates each frame, potentiallyusing significant computational resources in order to do so. Because ofresource competition and other conflicts, it is well know that in somesituations an application 112 may fail to present its frames at thespecified rate. Then, when resources become available, the application112 may produce all of the frames that it missed earlier and send thisseries of frames to the GPU 120. These frames may then be rendered at aninappropriate rate. When viewed by a user, the resulting motion can bejerky or may suffer from other annoyances. An override can be developedto address these issues.

In step 500 of FIG. 5 a, a frame produced by the application 112 isreceived by the CPU 102. This application-produced frame is sent to theGPU 120 in step 502 and is rendered in step 504. Turning to FIG. 6, thisapplication-produced frame 600 is rendered at the first frame time.

As steps 500 through 504 are performed (perhaps repeatedly for frameafter frame), an override 202 watches over this process. In step 506,the override 202 calculates (or otherwise determines) the time when anext frame needs to be presented. (In a very simple example, this wouldbe the frame time of the next frame, based solely on the frame time ofthe first frame and the known frame rate. In other embodiments, theoverride 202 may be working further ahead in the anticipated sequence offrames.)

Step 508 is, in some situations, technically optional. In this step, theoverride 202 produces its own frame to be displayed at the next frametime. There are several possible procedures for producing such a“synthetic” frame. In a sophisticated example, the override 202 couldexamine the past few application-produced frames, note any consistentmovement or other change in that short sequence, and then produce thesynthetic frame by predicting a continuation of that movement into thenext frame time. While the motion prediction may turn out to beincorrect, the viewed result would, in some situations, not be asjarring as simply repeating the last application-produced frame. Witheven more sophistication, the override 202 could gather furtherinformation from the hosting device 100 such as, for example, user-inputdata, and produce a scene graph based on the gathered information aswell as on the previously received application-produced frames. From thescene graph, the override 202 could predict the visual effects that theapplication 112 is trying to produce. The override 202 could thenproduce the synthetic frame accordingly.

The override 202 can use information beyond the previously receivedapplication-generated frames when creating the synthetic frame. As oneexample, the override 202 can monitor user inputs to the computingdevice 100. If a user moves the computing device 100 away from himself(as detected by, say, an accelerometer), then the override 202 cancreate a synthetic frame that is a zoomed-out perspective of theprevious application-produced frame. In another example, if the usertouches a position on a touch-sensitive display screen, then theoverride 202 can shift the viewer's point-of-view based on that touch(or on a more elaborate gesture). (This can be enabled, for example,when the input stream of graphics commands 200 b includes enoughinformation to draw a scene larger than that currently displayed orincludes enough information for the override 202 to create a scene graphof a fully three-dimensional scene.) In sum, the override 202 can applyuser-input information independently of mediation by the sourceapplication 112.

In step 510, the override 202, as it watches over the stream ofapplication-produced frames, decides whether or not the application 112is going to produce the next frame in time (an analysis based, in part,on the known frame rate). If it does, then everything is well, and thesynthetic frame produced in step 508 is discarded. (Another procedurewould be to only create the synthetic frame in step 508 if step 510determines that the synthetic frame is needed. That is why step 508 istechnically optional.)

If, on the other hand, the next application-produced frame is notavailable in time, then in step 512 of FIG. 5 b, the synthetic frameproduced in step 508 is sent to the GPU 120 where it is rendered at theappropriate frame time in step 514.

This method is illustrated in FIG. 6 where the application 112, afterproducing two frames 600 and 602 for the first and second frame times,fails to produce the next frame in time. The override 202 notes this andproduces a synthetic frame 604 for the third frame time. By the fourthframe time, the application 112 catches up and produces frame 606. (Ifthe application 112 also belatedly produces a frame for the third frametime, then in some embodiments, that frame is discarded.) After that,the application 112 fails to produce the next three frames in time, sothe override 202 produces synthetic frames 608, 610, 612.

The process of FIGS. 5 a and 5 b continues, looping as long as theapplication 112 is attempting to produce frames. Note, however, that insome situations, the process may not be looping on a strictlyframe-by-frame basis. Some applications 112 are able to produce a numberof frames at one time and to send the series of frames to the GPU 120 tobe rendered at the correct times. The teachings of FIGS. 5 a and 5 bapply to this scenario as well.

Finally, FIGS. 7 through 9 portray a scenario where an application 112is developed that depends upon the presence of an override. Thisscenario is called “A/B” testing. This is a way to guide productdevelopment by soliciting the input of users. In particular, two (ormore) sets of users are given copies of an application 112. However, notall copies are identical. Normally, one set of users receives a copythat embodies one choice for a design or functional element (e.g., the“A” version), while the other set of users gets a copy that embodies adifferent choice (the “B” version). Users provide feedback, and fromthat feedback it is determined which choice is more popular. Anadvantage of using an override is that the application 112 need not bechanged during testing: Only the overrides are different.

For more specific details of how overrides can assist in A/B testing,turn to FIG. 7 which shows a method for a server to gather user-responsedata in an A/B testing scenario. The application 112 is sent to a firstset of end-user devices 100 in step 700 along with instructions forgathering user-response data. (In some embodiments, a separate utilitymay be developed for gathering user-response data, and this utility neednot be sent along with the application 112 being tested.) (In someembodiments, the application 112 is not sent but is otherwise madeavailable to the end-user devices 100.) In the method of FIG. 7, thedesign or function choice being tested is embodied in a first override(version “A”), sent along with the application 112. For example, theoverride can turn the backgrounds behind all text messages produced bythe application 112 into a particular shade of blue.

FIG. 8 shows what can happen on the end-user device 100. In step 800,the end-user device 100 receives the application 112 along with theoverride (and, potentially, the instructions for gathering user-responsedata). The override is applied to the stream of graphics commandsproduced by the application 112 in step 802. User-response data (whichmay be explicitly queried for or may be implicitly derived frombehavioral observations of the user) are gathered in step 804 andreturned in step 806.

Returning to FIG. 7, the user-response data generated by the end-userdevice 100 using the method of FIG. 8 are received by the server in step702.

Steps 700 and 702 are repeated as steps 704 and 706 but with a differentoverride (the “B” version that, for example, turns the backgroundsbehind all text messages produced by the application 112 into a shade ofred) and, possibly, with a different set of end-user devices. This isillustrated at the first time increment of FIG. 9: The application 112is sent out with override A in 900 and with override B in 902.

The user responses to the “A” and “B” versions are compared to see whichversion is “better” in some sense (more popular, easier to use, maybemore efficient of computing resources). This is shown by 904 of FIG. 9where override B is preferred.

In optional step 708, the testing continues to refine the outcome bysending new overrides that embody new choices. In the case of FIG. 9,the previous winner override B is sent out again (906) to be testedagainst a new override C (908).

When testing is complete, and a final choice is selected forimplementation, that implementation may be coded into the application112 itself or, per optional step 710, the final implementation may beleft as an override shipped with the application 112. In FIG. 9,override C is the final winner (910).

In view of the many possible embodiments to which the principles of thepresent discussion may be applied, it should be recognized that theembodiments described herein with respect to the drawing figures aremeant to be illustrative only and should not be taken as limiting thescope of the claims. Therefore, the techniques as described hereincontemplate all such embodiments as may come within the scope of thefollowing claims and equivalents thereof.

We claim:
 1. On a computing device with a central processing unit and agraphics processing unit, a method for presenting graphical information,the method comprising: receiving, by the central processing unit, afirst input stream of graphics commands; applying, by the centralprocessing unit, an override to the first input stream of graphicscommands to produce a first output stream of graphics commands, theoverride comprising instructions for at least one graphics modification;sending, by the central processing unit to the graphics processing unit,the first output stream of graphics commands; and rendering, by thegraphics processing unit, the first output stream of graphics commands.2. The method of claim 1 wherein the first input stream of graphicscommands consists of a single graphics command.
 3. The method of claim 1wherein the override comprises instructions for a single graphicsmodification.
 4. The method of claim 1 wherein the override comprisesinstructions for a graphics modification selected from the groupconsisting of: an addition of a new graphics command to the first outputstream of graphics commands, a deletion of a graphics command from thefirst input stream of graphics commands, an amendment to a graphicscommand in the first input stream of graphics commands, and are-ordering of graphics commands in the first input stream of graphicscommands.
 5. The method of claim 1 wherein applying the overridecomprises creating a new output frame.
 6. The method of claim 5 whereincreating a new output frame based, at least in part, on an elementselected from the group consisting of: a current time and a desiredoutput frame rate.
 7. The method of claim 1 wherein applying an overridecomprises adding motion to the first output stream of graphics commands.8. The method of claim 1 wherein applying an override comprises:generating an input scene graph based, at least in part, on the firstinput stream of graphics commands; and applying at least a portion ofthe override to the input scene graph to create an output scene graph;wherein producing the first output stream of graphics commands is based,at least in part, on the output scene graph.
 9. The method of claim 8wherein applying at least a portion of the override to the input scenegraph comprises applying an element selected from the group consistingof: an element identifier, a shader, a properties module, and a physicsengine.
 10. The method of claim 1 wherein the first output stream ofgraphics commands consists of a single graphics command.
 11. The methodof claim 1 further comprising: receiving, by the central processingunit, a second input stream of graphics commands, the second inputstream distinct from the first input stream; applying, by the centralprocessing unit, at least a portion of the override to the second inputstream of graphics commands to produce a second output stream ofgraphics commands; sending, by the central processing unit to thegraphics processing unit, the second output stream of graphics commands;and rendering, by the graphics processing unit, the second output streamof graphics commands.
 12. The method of claim 11 wherein the overrideapplied to the first input stream of graphics commands is based, atleast in part, on the second input stream of graphics commands.
 13. Acomputing device configured for presenting graphical information, thecomputing device comprising: a central processing unit configured for:receiving a first input stream of graphics commands; applying anoverride to the first input stream of graphics commands to produce afirst output stream of graphics commands, wherein the override comprisesinstructions for at least one graphics modification; and sending, to agraphics processing unit, the first output stream of graphics commands;and the graphics processing unit distinct from, but operativelyconnected to, the central processing unit, the graphics processing unitconfigured for: receiving, from the central processing unit, the firstoutput stream of graphics commands; and rendering the first outputstream of graphics commands.
 14. The computing device of claim 13wherein the computing device is selected from the group consisting of: aset-top box, a personal communications device, a mobile telephone, apersonal digital assistant, a personal computer, a tablet computer, agaming console, a server, and a plurality of servers.
 15. The computingdevice of claim 13: wherein the computing device comprises a display;and wherein rendering the first output stream of graphics commandscomprises rendering graphical information to the display.
 16. Thecomputing device of claim 13: wherein the computing device comprises acommunications interface; and wherein rendering the first output streamof graphics commands comprises transmitting, via the communicationsinterface, a rendering of the first output stream of graphics commands.17. The computing device of claim 13: wherein the computing devicecomprises a memory; and wherein presenting the first output stream ofgraphics commands comprises writing a rendering of the first outputstream of graphics commands to the memory.
 18. The computing device ofclaim 13 wherein the central processing unit comprises a plurality ofprocessors.
 19. On a computing device with a graphics processing unit, amethod for presenting graphical information, the method comprising:receiving, by the graphics processing unit, a first input stream ofgraphics commands; receiving, by the graphics processing unit, anoverride; applying, by the graphics processing unit, the override to thefirst input stream of graphics commands to produce a first output streamof graphics commands, wherein the override comprises instructions for atleast graphics modification; and rendering, by the graphics processingunit, the first output stream of graphics commands.
 20. The method ofclaim 19: wherein the computing device comprises a central processingunit distinct from the graphics processing unit; and wherein receivingthe first input stream of graphics commands comprises receiving from aprocess running on the central processing unit.
 21. A computing deviceconfigured for presenting graphical information, the computing devicecomprising: a central processing unit; and a graphics processing unitdistinct from, but operatively connected to, the central processingunit, the graphics processing unit configured for: receiving a firstinput stream of graphics commands; receiving an override; applying theoverride to the first input stream of graphics commands to produce afirst output stream of graphics commands, wherein the override comprisesinstructions for at least one graphics modification; and rendering thefirst output stream of graphics commands.
 22. The computing device ofclaim 21 wherein receiving the first input stream of graphics commandscomprises receiving from a process running on the central processingunit.